The observation of the two different characteristic temperatures \(T_{ir}\)  and \(T_{sh}\)  associated with weak and strong irreversibilities, respectively, is interesting. In Fig. 1(c) and 1(d), we have shown the expanded view of the \(M-T\)  response at \(H\)  = 5 and 7 kOe to highlight these two irreversibility regions more clearly. Below \(T_{sh}\) , the \(ZFC\)  magnetization sharply drops and a strong irreversibility is observed. But, a weak irreversibility continues to exist until \(T_{ir}\)  which lies distinctly above T\(_{sh}\) . In Fig. 2(a), we have shown the variation of \(T_f\) , \(T_{sh}\)  and \(T_{ir}\)  with applied magnetic field. The observation of weak and strong irreversibilities below \(T_{ir}\)  and \(T_{sh}\) , respetively, in AuFe(11%) can prima facie be associated with the freezing of the transverse and longitudinal spin components respectively. According to the mean field theory of spin-glass, the G-T and the A-T lines vary in \(H-T\)  plane following \(H^{\alpha } \propto (1-\frac{T_g(H)}{T_g(0)})\) , with \(\alpha \)  = 2 and 2\(/\) 3 respectively [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. Here, \(T_g(0)\)  and \(T_g(H)\)  are the freezing temperatures at zero and finite fields \(\cite {gabay}\) . Therefore, the log-log plot of H and \(T_{ir}\)  and \(T_{sh}\)  should be linear in our AuFe(11%) sample, where the slope of the linear variation should give the value of \(\alpha \) . In the inset of Fig. 2(a), we have shown the double logarithmic plot of the \(T_{sh}\) , \(T_{ir}\)  and H for AuFe(11%) sample. It may be noted that these two temperatures are merged at low fields, and the log-log plot is linear only at higher fields. The linear fitting of the data in this range gives the value of the slope approximately \(\alpha \)  = 0.38 for both \(T_{sh}-H\) , and \(T_{ir}-H\)  lines, which is different from the expectation of mean field theory of spin-glass [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. In addition, in Fig. 2(a) we have presented the field dependence of the \(T_{min}\) , where the \(FCW\)  magnetization curve shows a minima. \(T_{min}\)  increases with increase in the field. However, at higher magnetic fields, a clear minimum in the \(FCW\)  magnetization curve is no longer visible.
